The present invention relates to a new and improved drive mechanism or apparatus for driving a shaft in a mobile apparatus.
In its more particular aspects, the drive mechanism of the present development is of the type comprising a drive unit releasably engageable with the shaft to be driven, the drive unit containing a drive chain, and at least two sprocket wheels guide the drive chain at an inner side thereof, one of the at least two sprocket wheels forming a driven sprocket wheel.
A drive mechanism of this kind is known, for example, from U.S. Pat. No. 3,762,662, granted Oct. 2, 1973, and is used for driving the shaft of a wind-up spool to wind-up a web of fabric. A first sprocket wheel is mounted to a shaft driven by a drive means. A second sprocket wheel is mounted at a driven or power take-off shaft and is driven by the first sprocket wheel by using a drive chain. The driven shaft is provided with clutch means for coupling the shaft of the wind-up spool with the driven shaft.
For exchanging a full wind-up spool against an empty spool the driving connection between the driven shaft and the shaft of the wind-up spool must be disengaged by actuating the clutch means. During the subsequent insertion of an empty wind-up spool the shaft thereof firstly must be brought into a position aligned with the driven shaft of the drive unit before the two shafts can be coupled to each other.
The establishment and the release of the driving connection between the driven shaft of the drive unit and the shaft of the wind-up spool thus requires a corresponding expense of work and time.
Another prior art construction of sheet winder is known from U.S. Pat. No. 4,150,797, granted Apr. 24, 1979.